季铵盐-醇疏水性低共熔溶剂分离镍和钴

Separation of cobalt and nickel by hydrophobic deep eutectic solvents based on quaternary ammonium salt and alcohols

疏水性低共熔溶剂(HDES)是一种新型的绿色溶剂,具有成本低、蒸汽压低和合成简单等优点。以三辛基甲基氯化铵(Aliquat 336)为氢键受体,正己醇、正辛醇、正癸醇、正十二醇和正十四醇分别为氢键供体制备了5种HDES,用于Co(Ⅱ)和Ni(Ⅱ)的萃取分离。考察了Cl-浓度、酸度和温度对萃取分离性能的影响,研究了Co(Ⅱ)的反萃行为,并采用紫外-可见吸收光谱和红外吸收光谱分析了HDES萃取Co(Ⅱ)的机理。结果表明,增加Cl-浓度、升高温度、降低酸度,可以改善Co(Ⅱ)和Ni(Ⅱ)的分离效果。不同的HDES相比,增加氢键供体的烷基链长度,Co(Ⅱ)和Ni(Ⅱ)的分配比略有下降,分离因子基本不变。萃入HDES的Co(Ⅱ)可采用1 mol·L^(-1)Na_(2)SO_(4)溶液反萃,经过二级反萃,可以将99.5%的Co(Ⅱ)反萃到水相。5种HDES萃取Co(Ⅱ)的机理相同,为阴离子交换。

Hydrophobic deep eutectic solvent(HDES)is a new type of green solvent with low cost,low vapour pressure,simple synthesis and other advantages.Using Aliquat 336 as hydrogen bond acceptor and hexyl alcohol,capryl alcohol,decyl alcohol,dodecyl alcohol,myristyl alcohol as hydrogen bond donor,respectively,five HDES were prepared for the extraction and separation of Co(Ⅱ)and Ni(Ⅱ).The effects of Cl-concentration,acidity and temperature were investigated,the stripping behavior of Co(Ⅱ)was studied,and the extraction mechanism of Co(Ⅱ)by HDES was studied by ultraviolet-visible spectroscopy and Fourier transform infrared spectroscopy.The results show that the separation performance of Co(Ⅱ)and Ni(Ⅱ)can be improved by increasing Cl-concentration,increasing temperature and decreasing acidity.Compared with different HDESs,the distribution ratios of Co(Ⅱ)and Ni(Ⅱ)decreased slightly with the increase of alkyl chain length in hydrogen bond donor,and the separation factors remained unchanged.The Co(Ⅱ)can be stripped from the HDESs phase with 1 mol·L^(-1) Na_(2)SO_(4) solution,and the stripping percentage reached 99.5%by two times of stripping.The extraction mechanism of Co(Ⅱ)by five HDESs is the same which accords with anion exchange.